Position measurement reference sheet, image forming apparatus, and image position measurement method
a technology of image forming apparatus and reference sheet, which is applied in the direction of electrical equipment, pictoral communication, etc., can solve the problems of reading error degrading accuracy and error arising from measurement errors
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first embodiment
[0065]Descriptions are given below of the measurement reference sheet and an image position measurement method using the measurement reference sheet according to a
[0066]In the first embodiment, a measurement reference sheet 26 illustrated in FIG. 3 is used. The measurement reference sheet 26 includes sheet detection windows 27a, 27b, and 27c (also collectively “sheet detection windows 27”) to detect the position of an end of the sheet P and image detection windows 28a, 28b, 28c, and 28d (also collectively “image detection windows 28”) to detect the position of the image on the sheet P. Relative positions among the sheet detection windows 27 and the image detection windows 28 of the measurement reference sheet 26 are accurately calculated and used to calculate the position of the sheet P and the position of the image on the sheet P.
[0067]In the image position measurement according to the present embodiment, the image B for adjustment (hereinafter also “adjustment image B”) is printed...
second embodiment
[0084]Next, descriptions are given below of a measurement reference sheet 262 according to a
[0085]As illustrated in FIG. 9, in the measurement reference sheet 262, the sheet detection windows 27 and image detection windows 28 are circular. Placement of the sheet detection windows 27 and the image detection windows 28 is similar to the placement thereof in the first embodiment, and thus only the sheet detection window 27a and the image detection window 28a are illustrated in FIG. 9. Similar to the first embodiment, relative positions of the sheet detection windows 27 and the image detection windows 28 on the measurement reference sheet 262 are accurately calculated and used to calculate the position of the sheet P and the image position on the sheet P.
[0086]In the second embodiment, in each of the detection windows, the density is measured in one direction, which is indicated by arrow Y5 in FIG. 9 (hereinafter “direction Y5”).
[0087]For example, in the sheet detection window 27a, the ...
third embodiment
[0110]In view of the foregoing, FIG. 14 illustrates a measurement reference sheet which is designed for image position measurement in a state in which the top of the scanner 40 is closed.
[0111]In the third embodiment, a liner 29 is disposed on the back (i.e., opposite the front face 260 facing the scanner glass 45) of the measurement reference sheet 262 as illustrated in FIG. 14. In the density measurement, the sheet P is interposed between the measurement reference sheet 262 and the liner 29. The liner 29 is a thin sheet similar to the measurement reference sheet 262.
[0112]With the liner 29, in a portion of the sheet detection windows 27 where the sheet P is not present, the density of a front side (facing the scanner glass 45) of the liner 29 is measured. The liner 29 has a color to exhibit a density (e.g., gray level) different from the density of the sheet P and that of the measurement reference sheet 262 to distinguish the boundaries of the liner 29, the sheet P, and the measu...
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